Bearing apparatus including a bearing assembly having a continuous bearing element and a tilting pad bearing assembly

ABSTRACT

Embodiments of the invention relate to bearing apparatuses including a bearing assembly having a continuous superhard bearing element including a continuous superhard bearing surface and a tilting pad bearing assembly. The disclosed bearing apparatuses may be employed in pumps, turbines or other mechanical systems. In an embodiment, the bearing apparatus includes a first and second bearing assembly. The first bearing assembly includes a first support ring and a plurality of tilting pads. Each tilting pad is tilted and/or tiltably secured relative to the first support ring. The second bearing assembly includes a continuous superhard bearing element. The continuous superhard bearing element includes a continuous superhard bearing surface facing the plurality of tilting pads and exhibits a maximum lateral width greater than about 2 inches.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/528,709 filed on May 22, 2017, which is a U.S. national stageapplication of PCT Application No. PCT/US2015/062434 filed on Nov. 24,2015, which claims priority to U.S. Provisional Application No.62/087,132 filed on Dec. 3, 2014, the disclosure of each of which isincorporated herein, in its entirety, by this reference.

BACKGROUND

Wear-resistant, superhard compacts are utilized in a variety ofmechanical applications. For example, polycrystalline diamond compacts(“PDCs”) are used in drilling tools (e.g., cutting elements, gagetrimmers, etc.), machining equipment, bearing apparatuses, wire-drawingmachinery, and in other mechanical apparatuses.

PDCs and other superhard compacts have found particular utility assuperhard bearing elements in thrust bearings within pumps, turbines,subterranean drilling systems, motors, compressors, generators,gearboxes, and other systems and apparatuses. For example, a PDC bearingelement typically includes a superhard polycrystalline diamond layerthat is commonly referred to as a diamond table. The diamond table isformed and bonded to a substrate using a high-pressure/high-temperature(“HPHT”) process.

A thrust-bearing apparatus includes a number of superhard bearingelements affixed to a support ring. The superhard bearing elements(e.g., a PDC bearing element) bear against other superhard bearingelements of an adjacent bearing assembly during use. Superhard bearingelements are typically brazed directly into a preformed recess formed ina support ring of a fixed-position thrust bearing.

Despite the availability of a number of different bearing apparatusesincluding such PDCs and/or other superhard materials, manufacturers andusers of bearing apparatuses continue to seek bearing apparatuses thatexhibit improved performance characteristics, lower cost, or both.

SUMMARY

Embodiments of the invention relate to bearing assemblies andapparatuses, which may be operated hydrodynamically. The disclosedbearing assemblies and apparatuses may be employed in bearingapparatuses for use in pumps, turbines, compressors, turbo expanders, orother mechanical systems.

In an embodiment, a bearing apparatus includes a first bearing assemblyand a second bearing assembly. The first bearing assembly includes afirst support ring and a plurality of tilting pads each of whichincludes a superhard bearing surface. Each tilting pad is tilted and/ortiltably secured relative to the first support ring. The second bearingassembly includes a continuous superhard bearing element. The continuoussuperhard bearing element includes a continuous superhard bearingsurface generally facing the superhard bearing surface of each of thetilting pads. Additionally, the continuous superhard bearing element hasa maximum lateral width greater than 5.1 cm (about 2 inches).

In an embodiment, the continuous superhard bearing element or asuperhard bearing element of at least one tilting pad may includepolycrystalline diamond, or a sintered or reaction-bonded ceramic (e.g.,reaction-bonded silicon carbide or reaction-bonded silicon nitride). Inan embodiment, the continuous superhard bearing element or a superhardbearing element of at least one tilting pad may have a surface finishless than about 0.64 micrometers (μm) (about 25 microinches).

Other embodiments are related to methods of using and manufacturingbearing apparatuses including a first bearing assembly having aplurality of tilting pads and a second bearing assembly having acontinuous superhard bearing element.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments of the present disclosure,wherein identical reference numerals refer to identical or similarelements or features in different views or embodiments shown in thedrawings.

FIG. 1A is an isometric view of a bearing assembly including continuoussuperhard bearing element having a continuous superhard bearing surfaceaccording to an embodiment.

FIG. 1B is an isometric partial cross-sectional view taken along theline 1B-1B of the bearing assembly of FIG. 1A.

FIG. 2A is an isometric view of a tilting pad thrust-bearing assemblyaccording to an embodiment.

FIG. 2B is an isometric partial cross-sectional view taken along line2B-2B of the tilting pad thrust-bearing assembly shown in FIG. 2A.

FIG. 2C is an isometric view of one of the tilting pads shown in FIGS.2A and 2B, with the tilting pad having a continuous superhard bearingsurface according to an embodiment.

FIG. 2D is a cross-sectional view taken along line 2D-2D of the bearingtilting pad shown in FIG. 2C.

FIG. 3 is a top plan view of a tilting pad including multiple segmentshaving serrated ends that form seams between the multiple segmentsaccording to another embodiment.

FIG. 4 is an isometric view of a tilting pad comprising a continuoussuperhard bearing element according to another embodiment.

FIG. 5A is an isometric cutaway view of an embodiment of athrust-bearing apparatus that may include a rotor having continuoussuperhard bearing element and a stator including tilting pads, with ahousing shown in cross-section.

FIG. 5B is a partial cross-sectional schematic representation of thethrust-bearing apparatus of FIG. 5A during use taken along line 5B-5Bthereof showing a fluid film that develops between the tilting pads ofthe stator and the continuous superhard bearing element of the rotor.

FIG. 6A is an exploded isometric view of a radial bearing apparatus thatmay include a rotor having a continuous superhard bearing element and astator including tilting pads according to an embodiment.

FIG. 6B is an isometric partial cross-sectional view of the stator ofthe radial bearing apparatus of FIG. 6A according to an embodiment.

FIG. 6C is an isometric partial cross-sectional view of the rotor of theradial bearing apparatus of FIG. 6A according to an embodiment.

FIG. 7 is a partial isometric cutaway view of a rotary system of aturbine according to an embodiment.

DETAILED DESCRIPTION

Embodiments of the invention relate to bearing assemblies andapparatuses, which may be operated hydrodynamically. The disclosedbearing assemblies and apparatuses may be employed in bearingapparatuses for use in pumps, turbines, compressors, turbo expanders, orother mechanical systems. Motor assemblies including at least one ofsuch bearing assemblies or apparatus are also disclosed, as well asmethods of using and fabricating such bearing assemblies and apparatusesutilizing superhard materials.

As will be discussed in more detail below, in one or more embodiments, abearing apparatus includes a first bearing assembly and a second bearingassembly. The first bearing assembly includes a first support ring and aplurality of tilting pads each of which includes a superhard bearingsurface. Each tilting pad is tilted and/or tiltably secured relative tothe first support ring. The second bearing assembly includes a secondsupport ring and a continuous superhard bearing element that is securedto the second support ring. The continuous superhard bearing elementincludes a continuous superhard bearing surface generally facing thesuperhard bearing surface of each of the tilting pads. In someembodiments, the continuous superhard bearing element has a maximumlateral width greater than about 5.1 cm (about 2 inches).

While the description herein provides examples relative to a pump orturbine bearing apparatus, the bearing assembly and apparatusembodiments disclosed herein may be used in any number of applications.For instance, the bearing assemblies and apparatuses may be used insubterranean drilling and motor assembly, motors, compressors, turboexpanders, generators, gearboxes, other systems and apparatuses, orcombinations of the foregoing. Furthermore, the bearing assemblies andapparatuses may also be operated hydrodynamically, partiallyhydrodynamically, or not hydrodynamically, if desired or needed.

FIGS. 1A and 1B are isometric and isometric partial cross-sectionalviews, respectively, of a thrust-bearing assembly 100 including acontinuous superhard bearing element 102 having a continuous superhardbearing surface 104. Such a configuration may improve wear performanceas compared to an assembly in which the overall bearing surface isformed of a plurality of segmented, discontinuous bearing surfacesdefined by the individual bearing elements. Additionally, such aconfiguration may improve wear performance and manufacturing costs ascompared to an assembly in which the overall bearing surface is formedof a plurality of segmented bearing elements that form a substantiallycontinuous bearing surface. Wear performance may be improved because thesubstantial absence of any discontinuities in the overall bearingsurface may minimize and/or prevent chipping and/or cracking of thecontinuous bearing surface 104, promote fluid film development and/orprevent fluid from leaking through seams formed between adjacentsuperhard bearing segments, increase fluid film strength, orcombinations thereof.

The continuous superhard bearing element 102 includes a continuoussuperhard bearing surface 104. The continuous superhard bearing surface104 has an integral construction such that a single superhard bearingelement forms the full continuous superhard bearing surface 104. Thecontinuous superhard bearing element 102 is attached to a support ring106 in a fixed position. For example, the support ring 106 may define arecess 114 that receives the continuous superhard bearing element 102partially therein. The continuous superhard bearing element 102 may besecured within the recess 114 to the support ring 106 by brazing,press-fitting, using fasteners, clamping, other type of mechanicalattachment, another suitable technique, or combinations thereof.However, in other embodiments, the support ring 106 may be omitted.

The support ring 106 may be made from a variety of different materials.For example, the support ring 106 may comprise carbon steel, stainlesssteel, copper (e.g., brass or bronze alloys), tungsten carbide, oranother suitable material.

The continuous superhard bearing surface 104 of the continuous superhardbearing element 102 may exhibit a relatively smooth surface finish. Inan embodiment, a bearing apparatus includes a thrust-bearing assemblythat includes continuous superhard bearing element 102 and anotherbearing assembly (e.g., a tilting pad bearing assembly). As thethrust-bearing assembly that includes the continuous superhard bearingelement 102 rotates relative to the other bearing surface of the otherbearing assembly, a fluid film may develop between the continuoussuperhard bearing surface 104 of the continuous superhard bearingelement 102 and the surface of the other bearing assembly, therebyincreasing the wear resistance and/or performance of the bearingapparatus. A smooth surface finish may facilitate the formation of thefluid film between the bearing surfaces of the bearing apparatus. Forexample, a surface defect caused by a rough surface finish (e.g., abump, a ridge, etc.) on the continuous superhard bearing surface 104 ofthe continuous superhard bearing element 102 may prevent the developmentof a sufficient fluid film at least proximate the defect. The surfacedefect may also increase the friction or contact between the bearingsurfaces. Such conditions may result in chipping, power losses, crackingor increased wear on both bearing surfaces. As such, the continuoussuperhard bearing surface 104 of the continuous superhard bearingelement 102 and/or the surface of the other bearing assembly may includea smooth surface finish. In an embodiment, the surface finish of thecontinuous superhard bearing surface 104 of the continuous superhardbearing element 102 or any other surface of the bearing apparatus (e.g.,the tilting pad bearing assembly) may have a surface finish less thanabout 0.89 μm (about 35 microinches) (e.g., less than about 0.64 μm(about 25 microinches), less than about 0.38 μm (about 15 microinches),less than about 0.25 μm (about 10 microinches), less than about 0.13 μm(about 5 microinches)) as measured, for example, by a profilometer byroot mean square (RMS). In another embodiment, the surface finish of thecontinuous superhard bearing surface 104 of the continuous superhardbearing element 102 or any other surface of the bearing apparatus mayhave a surface finish of about 0.64 μm (25 microinches) to about 0.89 μm(about 35 microinches), about 0.38 μm (about 15 microinches) to about0.64 μm (about 25 microinches), about 0.38 μm (about 15 microinches) toabout 0.51 μm (about 20 microinches), about 0.25 μm (about 10microinches) to about 0.38 μm (about 15 microinches), about 0.18 μm(about 7 microinches) to about 0.25 μm (about 10 microinches), about0.13 μm (about 5 microinches) to about 0.18 μm (about 7 microinches),about 0.064 μm (about 2.5 microinches) to about 0.13 μm (about 5microinches), less than about 0.064 μm (about 2.5 microinches), lessthan about 0.051 μm (about 2 microinches), less than about 0.025 μm(about 1 microinch), or submicrometers (submicroinches). The surfacefinish of any bearing surface of the bearing apparatuses disclosedherein may exhibit any of the disclosed surface finishes and may beselected based on the type of fluid used for lubrication of the bearingsurfaces, the expected fluid pressure or flow through the bearingapparatus, the expected rate of rotation, the expected load in thebearing apparatus and the expected tilting of any tilting pad in abearing assembly, other performance criteria, or combinations thereof.

The continuous superhard bearing element 102 may have a maximum lateralwidth “W,” such as a maximum diameter. In an embodiment, the maximumlateral width “W” of the continuous superhard bearing element 102 isgreater than about 5.1 cm (about 2 inches) (e.g., greater than about 7.6cm (about 3 inches), greater than about 12.7 cm (about 5 inches). Inanother embodiment, the maximum lateral width “W” of the continuoussuperhard bearing element 102 is about 5.1 cm (about 2 inches) to about7.6 cm (about 3 inches), about 7.6 cm (about 3 inches) to about 12.7 cm(about 5 inches), about 12.7 cm (about 5 inches) to about 17.8 cm (about7 inches), about 17.8 cm (about 7 inches) to about 25.4 cm (about 10inches), about 25.4 cm (about 10 inches) to about 30.5 cm (about 12inches) (e.g., 28 cm (about 11 inches)), or about 30.5 cm (about 12inches) to about 40.6 cm (about 16 inches). In some applications, themaximum lateral width “W” of the continuous superhard bearing element102 may be less than about 5.1 cm (about 2 inches). The maximum lateralwidth “W” of the continuous superhard bearing element 102 may be limitedat least partially based on the type of material used for the continuoussuperhard bearing element 102.

The continuous superhard bearing element 102 may be formed from of avariety of superhard materials. The term “superhard” means a materialhaving a hardness at least equal to the hardness of tungsten carbide,silicon carbide, or silicon nitride. In an embodiment, the continuoussuperhard bearing element 102 may include polycrystalline cubic boronnitride, polycrystalline diamond (e.g., formed by chemical vapordeposition or by HPHT sintering), diamond crystals, silicon carbide,silicon nitride, tantalum carbide, tungsten carbide (e.g., binderlesstungsten carbide, cobalt-cemented tungsten carbide), other metalcarbides, other superhard carbides, or combinations thereof. In anotherembodiment, the continuous superhard bearing element 102 may be composedof sintered or reaction-bonded silicon carbide, or sintered orreaction-bonded silicon nitride. The sintered or reaction-bonded siliconcarbide, or sintered or reaction-bonded silicon nitride may haveadditional materials therein. For example, the additional materials in asintered or reaction-bonded ceramic may include diamond, polycrystallinediamond, cubic boron nitride, a material exhibiting a hardness greaterthan the reaction-bonded ceramic or a material exhibiting a thermalconductivity greater than the reaction-bonded ceramic. Adding materialsto the sintered or reaction-bonded continuous superhard bearing elementmay increase the thermal conductivity and/or wear resistance ofcontinuous superhard bearing element 102. For example, adding diamondparticles to sintered or reaction-bonded silicon carbide, or sintered orreaction-bonded silicon nitride may increase the wear resistance of thecontinuous superhard bearing element 102 by more than 500%. In anembodiment, the diamond particles may be added to the sintered orreaction-bonded ceramic in an amount less that about 80 weight % (e.g.,about 50 weight % to about 80 weight %, about 25 weight % to about 50weight %, or less than about 25 weight %). Suitable reaction-bondedceramics from which the superhard bearing element 102 may be made arecommercially available from M Cubed Technologies, Inc. of Newark, Del.In an embodiment, the continuous superhard bearing element 102 may beformed from a single material or a single piece of any of the superhardmaterials disclosed herein.

In the illustrated embodiment, the continuous superhard bearing element102 includes a superhard table 108 defining the continuous superhardbearing surface 104 and a substrate 110 to which the superhard table 108is bonded. In an embodiment, the continuous superhard bearing element102 may be a polycrystalline diamond compact (“PDC”). The PDC includes apolycrystalline diamond (“PCD”) table defining the superhard table 108to which the substrate 110 is bonded. For example, the substrate 110 maycomprise a cobalt-cemented tungsten carbide substrate. The PCD tableincludes a plurality of directly bonded-together diamond grainsexhibiting diamond-to-diamond bonding therebetween (e.g., sp³ bonding),which define a plurality of interstitial regions. A portion of, orsubstantially all of, the interstitial regions of such the PCD table mayinclude a metal-solvent catalyst or a metallic infiltrant disposedtherein that is infiltrated from the substrate 110 or from anothersource. For example, the metal-solvent catalyst or metallic infiltrantmay be selected from iron, nickel, cobalt, and alloys of the foregoing.The PCD table may further include thermally-stable diamond in which themetal-solvent catalyst or metallic infiltrant has been partially orsubstantially completely depleted from a selected surface or volume ofthe PCD table 108, for example, an acid leaching process.

For example, appropriately configured PDCs may be used as the continuoussuperhard bearing element 102, which may be formed in an HPHT processes.Suitable PDCs having a PCD table with a maximum diameter over 6.4 cm(about 2.5 inches) are commercially available from Iljin Diamond Co.,Ltd. of Korea. For example, diamond particles may be disposed adjacentto the substrate 110, and subjected to an HPHT process to sinter thediamond particles to form the PCD table that bonds to the substrate 110,thereby forming the PDC. The temperature of the HPHT process may be atleast about 1000° C. (e.g., about 1200° C. to about 1600° C.) and thecell pressure of the HPHT process may be at least 4.0 GPa (e.g., about5.0 GPa to about 12 GPa or about 7.5 GPa to about 11 GPa) for a timesufficient to sinter the diamond particles.

The diamond particles may exhibit an average particle size of about 50μm or less, such as about 30 μm or less, about 20 μm or less, about 10μm to about 18 μm, or about 15 μm to about 18 μm. In some embodiments,the average particle size of the diamond particles may be about 10 μm orless, such as about 2 μm to about 5 μm or submicron. In someembodiments, the diamond particles may comprise a relatively larger sizeand at least one relatively smaller size. As used herein, the phrases“relatively larger” and “relatively smaller” refer to particle sizes (byany suitable method) that differ by at least a factor of two (e.g., 30μm and 15 μm). According to various embodiments, the mass of diamondparticles may include a portion exhibiting a relatively larger size(e.g., 30 μm, 20 μm, 15 μm, 12 μm, 10 μm, 8 μm) and another portionexhibiting at least one relatively smaller size (e.g., 6 μm, 5 μm, 4 μm,3 μm, 2 μm, 1 μm, 0.5 μm, less than 0.5 μm, 0.1 μm, less than 0.1 μm).In one embodiment, the diamond particles may include a portionexhibiting a relatively larger size between about 10 μm and about 40 μmand another portion exhibiting a relatively smaller size between about 1μm and 4 μm. In some embodiments, the diamond particles may comprisethree or more different sizes (e.g., one relatively larger size and twoor more relatively smaller sizes), without limitation. The PCD table 108so-formed after sintering may exhibit an average diamond grain size thatis the same or similar to any of the foregoing diamond particle sizesand distributions.

More details about diamond particle sizes and diamond particle sizedistributions that may be employed to form the PCD table in any of theembodiments disclosed herein are disclosed in U.S. patent applicationSer. No. 13/734,354; U.S. Provisional Patent Application No. 61/948,970;and U.S. Provisional Patent Application No. 62/002,001. U.S. patentapplication Ser. No. 13/734,354; U.S. Provisional Patent Application No.61/948,970; and U.S. Provisional Patent Application No. 62/002,001 areeach incorporated herein, in their entirety, by this reference.

In an embodiment, the superhard table 108 may be integrally formed withthe substrate 110. For example, the superhard table 108 may be asintered PCD table that is integrally formed with the substrate 110. Insuch an embodiment, the infiltrated metal-solvent catalyst from thesubstrate 110 may be used to catalyze formation of diamond-to-diamondbonding between diamond grains of the superhard table 108 from diamondpowder during HPHT processing. In another embodiment, the superhardtable 108 may be a pre-formed superhard table that has been HPHT bondedor brazed to the substrate 110 in a second HPHT process after beinginitially formed in a first HPHT process. For example, the superhardtable 108 may be a pre-formed PCD table that has been leached tosubstantially completely remove metal-solvent catalyst used in themanufacture thereof and subsequently HPHT bonded or brazed to thesubstrate 110 in a separate process.

In some embodiments, the superhard table 108 may be leached to deplete ametal-solvent catalyst or a metallic infiltrant therefrom in order toenhance the thermal stability of the superhard table 108. For example,when the superhard table 108 is a PCD table, the superhard table 108 maybe leached to remove at least a portion of the metal-solvent catalystfrom a working region thereof to a selected depth that was used toinitially sinter the diamond grains to form a leached thermally-stableregion. The leached thermally-stable region may extend inwardly from thecontinuous superhard bearing surface 104 to a selected depth. In oneexample, the depth of the thermally-stable region may be about 10 μm toabout 600 μm. More specifically, in some embodiments, the selected depthis about 50 μm to about 100 μm, about 200 μm to about 350 μm, or about350 μm to about 600 μm. The leaching may be performed in a suitableacid, such as aqua regia, nitric acid, hydrofluoric acid, or mixtures ofthe foregoing.

The substrate 110 may also be formed from any number of differentmaterials, and may be integrally formed with, or otherwise bonded orconnected to, the superhard table 108. Materials suitable for thesubstrate 110 may include, without limitation, cemented carbides, suchas tungsten carbide, titanium carbide, chromium carbide, niobiumcarbide, tantalum carbide, vanadium carbide, or combinations thereofcemented with iron, nickel, cobalt, or alloys thereof. For example, inan embodiment, the substrate 110 comprises cobalt-cemented tungstencarbide. However, in certain embodiments, the superhard tables 108 maybe omitted, and the continuous superhard bearing element 102 may be madefrom a superhard material, such as cobalt-cemented tungsten carbide. Inother embodiments, the substrate 110 may be omitted and the continuoussuperhard bearing element 102 may be a superhard material, such as apolycrystalline diamond body that has been leached to depletemetal-solvent catalyst therefrom or may be an un-leached PCD body.

A hole 112 may be formed in the continuous superhard bearing element 102using a variety of techniques. The hole 112 may be sized and configuredto receive a rotating shaft of pump, turbine, or other machine. In anembodiment, the hole 112 may be machined into a disk from which thecontinuous superhard bearing element 102 is made using electricaldischarge machining (e.g., plunge electrical discharge machining and/orwire electrical discharge machining), drilling, laser drilling, othersuitable techniques, or combinations thereof. For example, plungeelectrical discharge machining may be used to create a small starterthough hole in the disk from which the continuous superhard bearingelement 102 is made. Wire electrical discharge machining may then beused to enlarge the small starter though hole to form the hole 112. Inanother example, a laser is used to create the small starter throughhole or the laser may be used to form the hole 112. In anotherembodiment, a sacrificial material that is more easily removed than thesuperhard material from which the superhard bearing element 102 is mademay be used to define the hole 112 of the continuous superhard bearingelement 102. For example, a sacrificial material (e.g., tungsten,tungsten carbide, hexagonal boron nitride, or combinations thereof) islaterally surrounded by unsintered diamond particles and is thensubjected to an HPHT process. The sacrificial material is then removedfrom the PCD table so formed (e.g., mechanically, by blasting or via aleaching process) from the PCD surrounding it to form the hole 112.

In another embodiment, the continuous superhard bearing element 102 mayinclude a coating that forms the continuous superhard bearing surface104. The coating may be formed using a chemical vapor depositiontechnique, a physical vapor deposition technique, or any otherdeposition technique. For example, diamond may be deposited on a lesshard surface to form the continuous superhard bearing surface 104 usinga chemical or physical vapor deposition technique.

FIGS. 2A and 2B are isometric and isometric partial cross-sectionalviews, respectively, of a tilting pad thrust-bearing assembly 200according to an embodiment. The tilting pad thrust-bearing assembly 200includes a support ring 218 that carries a plurality ofcircumferentially spaced tilting pads 216. The tilting pads 216 mayinclude, for instance, fixed tilting pads, adjustable tilting pads,self-establishing tilting pads, other bearing pads or elements, orcombinations of the foregoing. Examples of tilting pad thrust-bearingassemblies for the tilting pad thrust-bearing assembly 200 are disclosedin U.S. Pat. No. 8,545,103, the disclosure of which is incorporatedherein, in its entirety, by this reference.

The bearing surface of each of the tilting pads 216 of the illustratedembodiment generally has a truncated pie-shaped geometry or a generallytrapezoidal geometry, and may be distributed about a thrust axis 220,along which a thrust force may be generally directed during use. Eachtilting pad 216 may be located circumferentially adjacent to anothertilting pad 216, with a circumferential space 222 or other offsettherebetween. For instance, the circumferential space 222 may separateadjacent tilting pads 216 by a distance of about 2.0 mm to about 20.0mm, or a distance of about 3.5 mm to about 15 mm, although theseparation distance may be greater or smaller. For instance, as the sizeof the tilting pad bearing assembly 200 increases, the size of thetilting pads 216 and/or the size of the circumferential space 222 mayalso increase. For example, the tilting pads 216 may exhibit a nominalradial width less than about 7.6 cm (about 3 inches) (e.g., less thanabout 5.1 cm (about 2 inches), less than about 2.5 cm (about 1 inch),less than 1.3 cm (about 0.5 inches), between 0.64 cm (about 0.25 inches)to about 1.3 cm (about 0.5 inches), between about 1.3 cm (about 0.5inches) to about 2.5 cm (about 1 inch), between about 2.5 cm (about 1inch) to about 5.1 cm (about 2 inches)). In other embodiment, thetilting pads 216 may exhibit a nominal radial width greater than about7.6 cm (about 3 inches).

Each tilting pad 216 may include a discrete superhard bearing element224, such that the tilting pads 216 collectively provide anon-continuous superhard bearing surface. The superhard bearing element224 may include a superhard table 226 that may be bonded to a substrate228. For example, the superhard bearing element 224 may be formed fromany of the materials and compacts previously described with respect tothe continuous superhard bearing element 102.

To support the tilting pads 216 of the tilting pad thrust-bearingassembly 200, the support ring 218 may define a channel 230 and thetilting pads 216 may be placed within the channel 230. In otherembodiments, the support ring 218 may define multiple pockets orotherwise define locations for the tilting pads 216. The tilting pads216 may then be supported or secured within the support ring 218 in anysuitable manner. For instance, as discussed hereafter, a pivotalconnection may be used to secure the tilting pads 216 within the supportring 218, although any other suitable securement or attachment mechanismmay also be utilized. The support ring 218 may also include an inner,peripheral surface defining a hole 212. The hole 212 may be generallycentered about the thrust axis 220, and may be adapted to receive ashaft (e.g., a downhole drilling motor shaft). The support ring 218 maybe formed of the same materials as the support ring 106.

In the illustrated embodiment, the tilting pad thrust-bearing assembly200 includes 10 tilt pads. In other embodiments, more or less than 10tilt pads may be used in the tilting pad thrust-bearing assembly 200.For example, between 3 to 16 tilt pads (e.g., 3 to 6, 6 to 8, 8 to 10,or 10 to 12) may be included in the tilting pad thrust-bearing assembly200. The number of tilt pads included in the tilting pad thrust-bearingassembly 200 may be chosen based on the expected load, the superhardmaterials of the continuous superhard bearing element 102 and thesuperhard bearing element 224, the size of the continuous superhardbearing element 102, and the desired life of the bearing apparatus.

In the embodiment illustrated in FIGS. 2A and 2B, the tilting pads 216may be used in connection with a runner or other superhard bearingelement (e.g., the continuous superhard bearing element 102 shown inFIG. 1A). In general, the tilting pad bearing assembly 200 may rotaterelative to a runner or other bearing assembly, while a lubricant orother fluid (e.g., seawater) floods the tilting pad bearing assembly 200and the runner/other bearing assembly. For example, as the runner 100 isrotated relative to a tilt pad bearing assembly 200, a fluid filmseparating the runner/other bearing assembly from a superhard bearingelement 224 may develop. For favorable use of the hydrodynamic forceswithin the lubricant, the tilting pads 216 may tilt which may result ina higher lubricant film thickness existing at a leading edge (i.e., anedge of a tilting pad 216 that would be traversed first by a referenceline on the runner while the runner 100 moves in the direction ofrotation), than at a trailing edge (i.e., an edge of a tilting pad 216over which such reference line is second to pass in the direction ofrotation), at which or near which a minimum film thickness may develop.The tilt pads may be manufactured such that respective superhard bearingsurfaces thereof exhibit the same or similar smooth surface finishes asthe continuous superhard bearing element 102, as previously described.Of course, in other embodiments, the tilt pad bearing assembly 200 mayrotate with respect to the runner 100, if desired, without limitation.

In the illustrated embodiment, each of the plurality of superhardbearing elements 224 is secured to a support plate 232 (FIG. 2B). Thesupport plate 232 may, for example, be formed of a metal, an alloy, acemented carbide material, other material, or any combination thereof.The substrate 228 of the superhard bearing element 224 may be secured tothe support plate 232 by brazing, welding, or other method. In someembodiments, the support plate 232 may define a pocket into which thesuperhard bearing segments may be tiltably or fixedly assembled and/orpositioned. In an embodiment, the support plate 232 has an integralconstruction such that a single body may form substantially the fullsupport plate 232. In other embodiments, multiple segments of one ormore materials may be used to form or define the support plate 232. Inanother embodiment, multiple superhard bearing segments may be used toform the superhard bearing element 224.

The degree to which the tilting pads 216 rotate or tilt may be varied inany suitable manner. For instance, in an embodiment, the tilting pads216 may be tilted about respective radial axes that extend generallyradially from the thrust axis 220. In FIG. 2B, the support plate 232 maybe attached to a pin 234. The pin 234 may, for example, be formed of ametal, an alloy, a cemented carbide material, other material, or anycombinations thereof. The pin 234 may be allowed to at least partiallyrotate, or may otherwise define or correspond to a tilt axis 236. Forexample, according to some embodiments, the pin 234 is journaled orotherwise secured within the support ring 218 in a manner that allowsthe pin 234 to rotate relative to the support ring 218. The pin 234 maybe fixed to the support plate 232 such that as the pin 234 rotatesrelative to the support ring 218, the support plate 232 may also rotateor tilt relative to the tilt axis 236 of the pin 234. The pin 234 andsupport plate 232 may rotate or tilt between zero and twenty degrees insome embodiments, such that the superhard bearing element 224 of therespective tilting pads 216 may also tilt between about zero and abouttwenty degrees relative to the pin 234 or other horizontal axis. Inother embodiments, the pin 234 and/or the superhard bearing element 224may rotate between about zero and about fifteen degrees, such as apositive or negative angle (θ) of about 0.5 to about 3 degrees (e.g.,about 0.5 to about 1 degree or less than 1 degree) relative to the tiltaxis 236 of the pin 234. In some cases, the support ring 218 may beconfigured for bidirectional rotation. In such a case, the pin 234 maybe allowed to rotate in clockwise and/or counter-clockwise directions.For example, the superhard bearing element 224 may thus tilt in eitherdirection relative to the axis of the pin 234 and/or the support ring218. For instance, the superhard bearing element 224 may be rotated to aposition anywhere between a positive or negative angle of about twentydegrees relative to an axis of the pin 234, such as a positive ornegative angle (θ) of about 0.5 to about 3 degrees (e.g., about 0.5 toabout 1 degree or less than 1 degree) relative to the tilt axis 236 ofthe pin 234.

The pin 234 may be used to allow one or more tilting pads 216 toselectively rotate. For instance, the tilting pads 216 may beself-establishing or limiting such that the tilting pads 216 mayautomatically or otherwise adjust to a desired tilt or other orientationbased on the lubricant used, the axial forces applied along the thrustaxis, the rotational speed of the runner and/or the tilting pad bearingassembly 200, other factors, or combinations of the foregoing. In stillother embodiments, the tilting pads 216 may be fixed at a particulartilt, or may be manually set to a particular tilt with or without beingself-establishing.

Further, the pin 234 represents a single mechanism for facilitatingrotation, translation, or other positioning of the tilting pads 216 soas to provide tilting pad superhard bearing element 224. In otherembodiments, other mechanisms may be used. By way of illustration,leveling links, pivotal rockers, spherical pivots, other elements, orany combination of the foregoing may also be used to facilitatepositioning of the tilting pads 216 in a tilted configuration. In anembodiment, the support plate 232 may be used to facilitate rotation ofa respective tilting pad 216. The support plate 232 may, for instance,be machined or otherwise formed to include a receptacle, an opening, orother structure into which the pin 234 may be at least partiallyreceived or secured. In embodiments in which the pin 234 is excluded,the support plate 232 may be machined or otherwise formed to includeother components, such as spherical pivot, pivotal rocker, or levelinglink interface. The support plate 232 may be formed of any suitablematerial, such as steel or other alloy; however, in some embodiments thesupport plate 232 is formed of a material that is relatively softer thanthe substrate 228, such that the support plate 232 may be relativelyeasily machined or formed into a desired shape or form. In otherembodiments, the support plate 232 can be eliminated and the substrate228 may be directly machined or formed to facilitate tilting of thetilting pad 216. Examples of tilting mechanisms that may be used fortilting the tilting pads disclosed herein are disclosed in U.S. PatentPublished Application No. 20140102810, the disclosure of which isincorporated herein, in its entirety, by this reference.

In some embodiments, the tilt axis of the tilting pads 216 may bealigned with a radial reference line dividing (e.g., symmetrically) thebearing surface 223. For example, where the support ring 218 may beconfigured for bi-directional rotation, the tilt axis of the tiltingpads 216 may be centered circumferentially between opposing edges of thetilting pads 216 (e.g., the leading edge and the trailing edge). Inother embodiments, the tilt axis of a tilting pad 216 may be offsetrelative to a center of the bearing surface 223 of the tilting pad 216.For example, where the support ring 218 is part of a rotor configuredfor only unidirectional rotation, the axis of rotation of the tiltingpad 216 may be offset such that the axis of rotation is closer to one ofthe leading edge or the trailing edge of the tilting pad 216. In otherembodiments, a tilt axis may be offset from a circumferential center ofits bearing surface despite a rotor being configured for bidirectionalrotation, or a tilt axis may be circumferentially centered despite arotor being configured for unidirectional rotation.

FIGS. 2C and 2D are isometric and cross-sectional views, respectively,of a single one of the tilting pads 216 shown in FIGS. 2A and 2B thatmay be used in connection with the tilting pad bearing assembly 200described above. The tilting pad 216 includes the continuous superhardbearing element 224. As previously discussed, each tilting pad 216 mayinclude the superhard table 226 bonded to the substrate 228, and thesubstrate 228 may further be secured within the support plate 232 bybrazing, using high temperature adhesives, press-fitting, fastening withfasteners, or other suitable attachment mechanism. In the illustratedembodiment, the support plate 232 may facilitate attachment of thesubstrate 228 to the support plate 232 by including an interior surface238 that defines an interior pocket 240. The interior pocket 240 may besized to generally correspond to a size of the substrate 228. It isnoted that the support plate 232 merely represents one embodiment for asupport plate and other configurations may be used. For example,according to another embodiment, a support plate may lack a pocket orother receptacle. In still another embodiment, the support plate may beeliminated.

In the illustrated embodiment, a superhard bearing surface 223 of thesuperhard bearing element 224 (e.g., the superhard table 226) issubstantially planar, although such an embodiment is merelyillustrative. In other embodiments, the superhard bearing surface 223 ofthe superhard bearing element 224 may be curved, or have another contouror topography. Moreover, outer edges of the superhard bearing element224 may optionally include a chamfer 242. The chamfer 242 may be formedby placing a chamfer on the individual outer edge regions of thesuperhard bearing element 224 or, if present, the superhard table 226.The superhard bearing element 224 may also take a number of other forms.For example, in FIG. 2C, the superhard bearing surface 223 issubstantially pie-shaped with a chamfered edge. In other embodiments,the edges of a superhard bearing element 224 may define other shapes,including radiused, arcuate, generally circular, generally elliptical,generally trapezoidal, other shaped surfaces, or may form a sharp edge,or combinations thereof.

FIGS. 3 and 4 illustrate top plan and isometric views, respectively, ofdifferent embodiments of tilting pads that may be employed in a tiltingpad bearing assembly according to an embodiment. FIG. 3 illustrates atilting pad 316 that may include a plurality of superhard bearingsegments 344 a-d, each of which includes a superhard bearing element 324that may include a superhard table 326 bonded to a substrate (notshown). The superhard table 326 and substrate (not shown) is optionallybonded or otherwise connected to a support plate 332. Each superhardtable 326 includes a superhard bearing surface 327 that collectivelyform a larger, substantially continuous superhard bearing surface.

The superhard bearing segments 344 a-d each may include an outer edgeregion 346 and an interior edge region 348. The superhard bearingsegments 344 a-d may be configured with a serrated geometry at theinterior edge regions 348. Such a configuration may allow adjacentsuperhard bearing segments 344 a-d to mate and at least partiallyinterlock, while also defining seams 350 of a geometry that limits fluidleakage radially through the gaps between adjoining superhard bearingsegments 344 a-d.

The illustrated and described seams 350 between adjacent superhardbearing segments 344 are merely illustrative, and seams 350 betweensuperhard bearing segments 344 and/or configurations of interior edgeregions 348 of superhard bearing segments 344 may have any number ofconfigurations. For, instance, a set of interconnecting superhardbearing segments may have substantially straight, serrated, saw-toothed,sinusoidal-like, curved, or otherwise shaped interior edge regions, orany combination of the foregoing. Moreover, some portions of an interioredge region may have one configuration of shape while another portion ofan interior edge region on the same superhard bearing segment may have adifferent configuration or shape. Accordingly, different superhardbearing segments may also include different mating geometry or otherconfigurations. The plurality of superhard bearing segments 344 a-d mayhave a coating thereon that at least partially fills the seams 350. Thecoating may be applied using chemical vapor deposition, physical vapordeposition, other deposition techniques or combinations thereof.Additionally, sealant materials may at least partially fill the seams350, such as braze alloy, tungsten carbide, polycrystalline diamond,other ceramic materials, or combinations thereof.

As discussed herein, a tilting pad bearing assembly including superhardbearing segments may be utilized where certain conditions are met, or inany number of other circumstances or industries. For instance, anapplication may be identified where it would benefit to use a superhardbearing element including a superhard material. However, the superhardmaterial may have associated production limits (e.g., size,availability, etc.). Where the superhard bearing element has a size,shape, or other feature(s) exceeding such production limits, thesuperhard bearing element may be fashioned out of multiple individualsegments that collectively define a superhard bearing surface of thesuperhard bearing element. In other cases, however, the type of materialused in the superhard bearing element may not have the same productionlimits as PDCs or other superhard materials, or the superhard bearingelement may be sized small enough to allow a single superhard or othermaterial to be used to form the superhard bearing surface.

FIG. 4 illustrates an embodiment in which a tilting pad 416 may have asize and/or comprise a material configured such that a single segmentmay form a substantially continuous surface of the superhard bearingelement 424. In particular, the tilting pad 416 may include a superhardtable 426 bonded to a substrate 428. The substrate 428 may in turn bebonded to a support plate 432. Optionally, the support plate 432 isoversized relative to the substrate 428; however, the support plate 432may also be about the same size or smaller than the substrate 428. Inthis embodiment, a single element may define substantially the entiresuperhard bearing element 424. For instance, the element may exhibit alength and/or width that may measure approximately 15 mm by 10 mm, suchthat a single superhard table 426 made from polycrystalline diamond orother materials may be fashioned into the desired shape, even in theabsence of providing multiple interlocking, adjoining, or adjacentsegments. In other embodiments, the element may have other sizes and mayeven exceed a maximum size available for PDCs. For instance, othersuperhard materials (e.g., tungsten carbide, reaction-bonded ceramics,reaction-bonded ceramics containing diamond particles) or any othersuperhard material disclosed herein may be used to form the superhardbearing element 424 using a single, integral segment.

Any of the above-described embodiments including a bearing assemblyhaving a continuous superhard bearing element and/or a tilting padbearing assembly may be employed in a thrust-bearing apparatus. Forexample, a thrust-bearing apparatus may include a rotor configured asthe thrust-bearing assembly 100 and a stator configured as the tiltingpad thrust-bearing assembly 200, although any combination of the bearingassemblies with the continuous superhard bearing element and a tiltingpad bearing assembly may be employed in other embodiments. FIGS. 5A isan isometric cutaway view of a thrust-bearing apparatus 500 according toan embodiment. FIG. 5B is a partial cross-sectional schematicrepresentation of a thrust-bearing apparatus 500 during use. One of thebearing assemblies is a stator while the other bearing assembly is arotor. In the illustrated embodiment, the tilting pad bearing assemblyis a stator 552 and the bearing assembly having the continuous superhardbearing element is a rotor 554. The stator 552 and rotor 554 may beconfigured as any of the described embodiments of bearing assemblies.The terms “rotor” and “stator” refer to rotating and stationarycomponents of the tilting pad bearing apparatus 500, respectively,although the rotating and stationary status of the illustratedembodiments may also be reversed.

The stator 552 may include a support ring 506 and a plurality of tiltingpads 516 mounted or otherwise attached to a support ring 518, with eachof the tilting pads 516 having a superhard bearing element. The tiltingpads 516 may be tilted and/or tilt relative to a rotational axis 520 ofthe thrust-bearing apparatus 500 and/or one or more surfaces of thesupport ring 506. The tilting pads 516 may be fixed at a particulartilt, may be manually adjusted to exhibit a particular tilt, mayself-establish at a particular tilt, or may be otherwise configured.

The rotor 554 may be configured in any suitable manner, including inaccordance with any of the embodiments described herein. The rotor 554may include a support ring 506 connected to continuous superhard bearingelement 502. The continuous superhard bearing element 502 of the rotor554 is generally adjacent to the superhard bearing elements of thestator 552. A fluid film may develop between the continuous superhardbearing element 502 of the rotor 554 and the superhard bearing elementof the stator 552. The continuous superhard bearing element 502 may bemounted or otherwise attached to a support ring 518 by brazing, apress-fit, mechanical fasteners, or in another manner.

As shown in FIG. 5A, a shaft 556 may be coupled to the support ring 506and operably coupled to an apparatus capable of rotating the shaftsection 556 in a direction R (or in an opposite direction). For example,the shaft 556 may extend through and may be secured to the support ring506 of the rotor 554 by press-fitting or a threaded connection thatcouples the shaft 556 to the support ring 506, or by using anothersuitable technique. A housing 558 may be secured to the support ring 518of the stator 552 by, for example, press-fitting or threadly couplingthe housing 558 to the support ring 518, and may extendcircumferentially about the shaft 556, the stator 552, and the rotor554.

The operation of the thrust-bearing apparatus 500 is discussed in moredetail with reference to FIG. 5B. FIG. 5B is a partial cross-sectionalschematic representation in which the shaft 556 and housing 558 are notshown for clarity. In operation, lubrication, drilling fluid, mud, orsome other fluid may be pumped between the shaft 556 and the housing558, and between the tilting pads 516 of the stator 552 and thecontinuous superhard bearing element 502 of the rotor 554. Moreparticularly, rotation of the rotor 554 at a sufficient rotational speedmay sweep the fluid onto superhard bearing elements of the stator 552and may allow a fluid film 560 to develop between the continuoussuperhard bearing element 502 of the rotor 554 and the superhard bearingelement of the stator 552. The fluid film 560 may develop under certainoperational conditions in which the rotational speed of the rotor 554 issufficiently great and the thrust load is sufficiently low.

In an embodiment, the tilting pads 516 may be positioned at a fixed tiltangle or at a configurable or self-establishing tilt angle. The tiltingpads 516 of the stator 552 may have a leading edge 562 at a differentposition than a trailing edge 564 relative to the rotor 554. Forinstance, in FIG. 5B, the tilting pads 516 may be tilted such that agreater separation exists between the tilting pads 516 and thecontinuous superhard bearing element 502 at a leading edge 562(illustrated on one tilting pad 516) than at a trailing edge 564(illustrated on another tilting pad 516, for clarity). Under suchcircumstances, the lubricant film 560 may have a variable thicknessacross the tilting pad 516. In this particular embodiment, a higherlubricant film thickness may exist at the leading edge 562 than at thetrailing edge 564.

Under certain operational conditions, the pressure of the fluid film 560may be sufficient to substantially prevent contact between thecontinuous superhard bearing element 502 of the rotor 554 and thesuperhard bearing elements of the stator 552 and thus, may substantiallyreduce wear of the continuous superhard bearing element 502 and thesuperhard bearing elements. When the thrust loads exceed a certain valueand/or the rotational speed of the rotor 554 is reduced, the pressure ofthe fluid film 560 may not be sufficient to substantially prevent thecontinuous superhard bearing element 502 of the rotor 554 and thesuperhard bearing elements of the stator 552 from contacting each other.Under such operational conditions, the thrust-bearing apparatus 500 isnot operated as a hydrodynamic bearing. Thus, under certain operationalconditions, the thrust-bearing apparatus 500 may be operated as ahydrodynamic bearing apparatus and under other conditions thethrust-bearing apparatus 500 may be operated so that the continuoussuperhard bearing element 502 and superhard bearing elements of thetilting pad 516 contact each other during use or a partially developedfluid film is present between the continuous superhard bearing element502 and superhard bearing elements of the tilting pad 516. However, thesuperhard bearing elements of the plurality of tilting pads 516 andcontinuous superhard bearing element 502 may comprise superhardmaterials that are sufficiently wear-resistant to accommodate repetitivecontact with each other, such as during start-up and shut-down of asystem employing the thrust-bearing apparatus 500 or during otheroperational conditions not favorable for forming the fluid film 560. Instill other embodiments, a backup roller or other bearing (not shown)may also be included for use during certain operational conditions, suchas during start-up, or as the fluid film 560 develops.

In an embodiment, the continuous superhard bearing element 502 and oneor more of the plurality of tilt pads 516 may be formed from differentmaterials. For example, the continuous superhard bearing element 502 maybe formed from any of the reaction-bonded ceramics disclosed herein(e.g., reaction-bonded silicon carbide or reaction-bonded siliconnitride with or without diamond) and the bearing elements of each tiltpads 516 may be formed from a PDC or any other type of polycrystallinediamond element disclosed herein. Because the superhard bearing surfaceof the continuous superhard bearing element 502 and one or more tiltpads 516 may include different materials, a non-diamond bearing surfacemay wear preferentially relative to wear of a polycrystalline diamondbearing surface. Providing such a bearing assembly including differentmaterial bearing surfaces may provide for better heat transfer andbetter maintenance of the fluid film 560 between the superhard bearingsurfaces of the continuous superhard bearing element 502 and thesuperhard bearing elements of the tilting pad 516 than if all thesuperhard bearing surfaces included the same non-diamond superhardmaterial (e.g., where both include silicon carbide).

Polycrystalline diamond and reaction-bonded ceramics containing diamondparticles have substantially higher thermal conductivity than superhardcarbides, such as sintered silicon carbide, reaction-bonded siliconcarbide, or tungsten carbide. Because one of the superhard bearingsurfaces of the continuous superhard bearing element 502 or thesuperhard bearing element of the tilting pad 516 includespolycrystalline diamond or reaction-bonded ceramics containing diamondparticles, heat generated during use (e.g., at non-diamond bearingsurfaces) may be better dissipated as a result of its proximity orcontact with polycrystalline diamond bearing surfaces. Thus, a bearingassembly including a polycrystalline diamond or reaction-bonded ceramicscontaining diamond particles bearing surfaces may provide increased wearresistance as compared to a bearing assembly in which all the bearingsurfaces include a non-diamond superhard materials (e.g., siliconcarbide), but at significantly lower cost than would be associated witha bearing assembly in which both of the opposed bearing surfaces includeonly polycrystalline diamond.

In an embodiment, at least one superhard bearing element of the stator552 may include at least one non-diamond superhard bearing surface, suchas only including non-diamond bearing surfaces. Meanwhile the rotor 554may include a polycrystalline diamond continuous superhard bearingelement 502. The stator 552 within the tilting pad bearing apparatus 500often fails before the rotor 554. In some instances, this may occurbecause the stator 552 bearing surfaces are often subjected to unequalheating and wear. For example, wear on the stator 552 is often unequalas a result of a small number of stator 552 bearing elements beingssomewhat more “prominent” than the other stator 552 bearing elements. Asa result, contact, heating, and wear during use may be preferentiallyassociated with these more prominent stator 552 bearing elements. Forexample, the bulk of the load and resulting wear may be borne by, forexample, the one to three most prominent bearing elements, while theother stator 552 bearing elements may show little wear by comparison.Such wear may result from the difficulty of perfectly aligning thebearing elements of the bearing assembly.

Because the stator 552 may typically wear faster than the rotor, in anembodiment the stator 552 bearing elements may not include diamond, butinclude a non-diamond superhard material, as the stator 552 may failfirst. In such an embodiment, the stator 552 may be replaced oncefailure or a given degree of wear occurs. In another embodiment, thestator 552 may include at least one, one or more, or only diamondbearing surfaces, and the rotor 554 may not include a diamond bearingsurface. It is currently believed that having at least one diamondsurface and at least one non-diamond surface facilitates faster breakingin of the bearing surfaces as the less hard bearing surfaces wear/breakin relatively faster. In other embodiments, both the continuoussuperhard bearing element 502 and the superhard bearing elements of eachtilt pads 516 may be formed from a PDC, diamond or any other type ofpolycrystalline diamond element disclosed herein. In another embodiment,both the continuous superhard bearing element 502 and the superhardbearing elements of each tilt pads 516 may be formed fromnon-polycrystalline diamond materials such as reaction-bonded ceramicsor other superhard materials. In yet another embodiment, the continuoussuperhard bearing element 502 may be formed from non-polycrystallinediamond materials such as reaction-bonded ceramics or other superhardmaterials, and the superhard bearing elements of each tilt pads 516 maybe PDCs or other type of polycrystalline diamond elements.

The concepts used in the thrust-bearing assemblies and apparatusesdescribed herein may also be employed in radial bearing assemblies andapparatuses. FIGS. 6A to 6C are isometric, exploded, and isometricpartial cross-sectional views, respectively, of a radial bearingapparatus 600 according to yet another embodiment. The radial bearingapparatus 600 may include an inner race 654 (e.g., a runner or rotor)that may have an interior surface 668 defining an hole 612 for receivinga shaft or other component. The inner race 654 may also include acontinuous superhard bearing element 602 positioned at or near anexterior surface 670 of the inner race 654. The continuous superhardbearing element 602 may include a convexly-curved continuous superhardbearing surface 604 and may be formed from any of the materialspreviously discussed for use with the continuous superhard bearingelement 102.

The support ring 606 of the inner race 654 may include acircumferentially-extending recess that receive the continuous superhardbearing element 602. The continuous superhard bearing element 602 may besecured within the recess or otherwise secured to the support ring 606by brazing, press-fitting, using fasteners, or another suitabletechnique. The support ring 606 may also define an interior surface 668defining an opening 612 that is capable of receiving, for example, ashaft (not shown) or other apparatus.

The radial bearing apparatus 600 may further include an outer race 652(e.g., a stator) configured to extend about and/or receive the innerrace 654. The outer race 652 may include a plurality ofcircumferentially-spaced tilting pads 616, each of which may include asuperhard bearing element 624. A superhard bearing surface of thesuperhard bearing element 624 may be substantially planar, although inother embodiments the surface of the superhard bearing element 616 maybe a concavely-curved superhard bearing surface to generally correspondto shapes of convexly-curved continuous superhard bearing surface 604 ofthe inner race 654. The terms “rotor” and “stator” refer to rotating andstationary components of the radial bearing system 600, respectively.Thus, if the inner race is configured to remain stationary, the innerrace may be referred to as the stator and the outer race may be referredto as the rotor.

Rotation of a shaft (not shown) secured to the inner race 654 may effectrotation of the inner race 654 relative to the outer race 652. Drillingfluid or other fluid or lubricant may be pumped between the continuoussuperhard bearing surface 604 of the continuous superhard bearingelement 602 of the inner race 654 and the surface of the superhardbearing element 624 of the outer race 652. When the inner race 654rotates, the leading edge sections of the tilting pads 616 may sweeplubricant (e.g., drilling fluid or other lubricant) onto the surface ofthe superhard bearing element 624 of the outer race 652. As previouslydescribed with respect to the hydrodynamic tilting pad bearing apparatus500, at sufficient rotational speeds for the inner race 654, a fluidfilm may develop between the superhard bearing element 624 of thetilting pads 618 and the continuous superhard bearing element 602, andmay develop sufficient pressure to maintain the superhard bearingelement 624 and the continuous superhard bearing element 602 apart fromeach other. Accordingly, wear on the superhard bearing element 624 andcontinuous superhard bearing element 602 may be reduced compared to whendirect contact between superhard bearing element 624 and continuoussuperhard bearing element 602 occurs.

As further illustrated in FIGS. 6A and 6B, the outer race 652 includes asupport ring 618 extending about an axis 620. The support ring 618 mayinclude an interior channel 630 configured to receive a set of tiltingpad 616 superhard bearing elements 624 distributed circumferentiallyabout the axis 620. Each tilting pad 616 may include a superhard table626. The superhard bearing element 624 may be curved (e.g.,concavely-curved) or substantially planar and, in some embodiments, mayinclude a peripheral chamfer. The tiling pad 616 may be formed from anyof the superhard materials and structures disclosed herein. In otherembodiments, the superhard bearing element 624 may be otherwise curved,lack a chamfered edge, may have another contour or configuration, or anycombination of the foregoing. Each superhard table 626 may be bonded toa corresponding substrate 628. Further, each superhard bearing element624 may be tilted circumferentially relative to an imaginary cylindricalsurface. The superhard tables 626 and substrates 628 may be fabricatedfrom the same materials described above for the tilting pads 216 shownin FIGS. 2A and 2B.

Each superhard bearing element 624 of a corresponding tilting pad 616may be tilted in a manner that facilities sweeping in of a lubricant orother fluid to form a fluid film between the inner race 654 and theouter race 652. Each tilting pad 616 may be tilted and/or tilt about anaxis that is generally parallel to the central axis 620. As a result,each tilting pad 616 may be tilted at an angle relative to the inner andouter surfaces of the ring 618 and in a circumferential fashion suchthat the leading edges of the tilting pads 616 are about parallel to thecentral axis 620. The leading edge may help to sweep lubricant oranother fluid onto the surfaces of the superhard bearing elements 624 ofthe stator 652 to form a fluid film in a manner similar to the tiltingpads 516 shown in FIGS. 5A and 5B. More particularly, when the innerrace 654 is concentrically positioned relative to the outer race 652,the leading edges may be offset relative to the outer edge of the outerrace 652, and by a distance that is larger than a distance between theouter race 652 and a trailing edge of the superhard bearing surface 624.It should be noted that in other embodiments, the radial bearingapparatus 600 may be configured as a journal bearing. In such anembodiment, the inner race 654 may be positioned eccentrically relativeto the outer race 652.

In some embodiments, the tilting pad 616 may be formed from a pluralityof superhard bearing segments (not shown) that collectively define arespective tilting pad 616. Each superhard bearing segment may besubstantially identical, or the superhard bearing segments may bedifferent relative to other of the superhard bearing segments. In someembodiments, the superhard bearing segments each include a superhardtable 626 bonded to a substrate 628 as described herein. Optionally, thesubstrate 628 may be connected or supported relative to a support plate632, the support ring 618, or other material or component. Additionally,seams (not shown) may be formed between circumferentially and/orlongitudinally adjacent to the superhard bearing elements 604. The edgesof the superhard bearing segments 626 may have any number ofconfigurations or shapes, and may correspond to or interlock withadjoining edges in any number of different manners. Further, sealantmaterials may be disposed within a gap (not shown) that may be formedbetween adjacent superhard bearing segments to help further preventfluid leakage through the seams.

FIG. 7 is a partial isometric cutaway view of an embodiment of a turbinesystem 700, such as a wind turbine system, which may incorporate any ofthe bearing apparatus embodiments disclosed herein. The turbine system700 may include a housing 758 and a main gear shaft 756 operablyconnected to another device such as a wind turbine, i.e., bladesattached to a hub, (not shown). At least one rotor 754 including acontinuous superhard bearing element 702 may be operably connected tothe main shaft 756. For example, the rotor 754 may be configured as thebearing assembly 100 shown in FIG. 1 or any other bearing assemblyincluding a continuous superhard bearing element disclosed herein. Atleast one stator 752 including a plurality of tilting pads may beconnected to the housing 758. For example, the stator 752 may beconfigured as the bearing assembly 200 shown in FIG. 2A or any othertilting pad bearing assembly disclosed herein. The stator 752 or therotor 754 may be a split bearing (e.g., manufactured in multiplecomponents) to facilitate assembly. The shaft 756 may extend through acentral hole 712 in the rotor 754 and stator 752 and may be secured toeach rotor 754 by press fitting or otherwise attaching the gear shaft756 to each rotor 754 bearing assembly, threadly coupling the shaft 756to each rotor 754 bearing assembly, or another suitable technique. Inthe illustrated embodiment, the wind turbine system includes two bearingapparatuses. However, in other embodiments, the wind turbine system mayinclude one or more bearing apparatuses (e.g., one bearing apparatus, orthree or more bearing apparatuses).

In an embodiment, the rotor 754 may include a support ring 706 and acontinuous superhard bearing element 702 attached or bonded to thesupport ring 706. The continuous superhard bearing element 702 includesa continuous superhard bearing surface 704. The continuous superhardbearing element 702 may include a superhard table 708 bonded to asubstrate 710. Similarly, the stator 752 may include a support ring 718having a channel 730 therein and a plurality of tilt pads 716 positionedinside the channel 730. The plurality of tilting pads 716 may include asuperhard bearing element 724 that may have a superhard bearing table726 bonded to a substrate 728. The plurality of tilting pads 716 mayfurther include a support plate 732 above a pin 734 wherein thesuperhard bearing element 724 is bonded or attached to the support place732. While the stator 752 bearing assembly and the rotor bearingassembly 754 is shown including only one row of the superhard bearingelements 724 and 702, respectively, the stator 752 bearing assembly andthe rotor bearing assembly 754 may include two rows, three rows, or anynumber of suitable rows of the superhard bearing elements.

In an embodiment, wind may turn the blades on the wind turbine (notshown), which in turn may rotate the main shaft 756 about a rotationaxis 720. The main shaft 756 may rotate the rotor 754 bearing assemblyabout the rotation axis 720. As shown, the main shaft 756 may go througha gear transmission box 766. For example, the main shaft 774 may beconnected to a first gear 776 that turns a second gear 778 or viceversa. The first gear 776 may be larger than the second gear 778. Thesecond smaller gear 778 may be connected to a shaft 780 that turns agenerator (not shown) to produce electricity.

As wind speed increases and energy builds within the system 700, thehigh thermal conductivity of a diamond or other high thermalconductivity bearing element may help remove heat from the contactsurface between the surfaces of the bearing assemblies. Such aconfiguration may help reduce the likelihood of temperature inducedstrength reductions and/or failure in the bearing assemblies. Further,in an embodiment where either the continuous superhard bearing element702 and at least one of the superhard bearing elements 724 of the tiltpads 716 are formed of more than one material, the modulus contrastbetween materials may help provide resistance to shock and vibrationloading. Such a configuration may help reduce the likelihood offretting, micro pitting, and/or other types of wear in the rotor 754 andstator 752 bearing assemblies. This may be advantageous given thefrequent starts and stops of the system 700. Moreover, in an embodiment,differences between the elasticity of superhard materials may helpreduce the likelihood of adhesion.

While the bearing apparatus including the rotor 754 and the stator 752is shown in a turbine application, the bearing apparatus may be used inother diverse applications. For example, the bearing apparatusesdisclosed herein may be used in subterranean drilling and motorassembly, motors, pumps, compressors, generators, gearboxes, and othersystems and apparatuses, or in any combination of the foregoing.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiment disclosed herein are for purposes of illustration and are notintended to be limiting. Additionally, the words “including,” having,”and variants thereof (e.g., “includes” and “has”) as used herein,including the claims, shall be open ended and have the same meaning asthe word “comprising” and variants thereof (e.g., “comprise” and“comprises”).

We claim:
 1. A bearing apparatus, comprising a first bearing assemblyincluding: a first support ring; and a plurality of tilting pads each ofwhich includes a superhard bearing element having a superhard bearingsurface, each of the plurality of tilting pads tilted and/or tiltablysecured relative to the first support ring; and a second bearingassembly including: a continuous superhard bearing element including acontinuous superhard bearing surface that generally faces the superhardbearing element of each of the plurality of tilting pads, the continuoussuperhard bearing element having a maximum lateral width greater thanabout 12.7 cm.
 2. The bearing apparatus of claim 1 wherein the superhardbearing surface of at least one of the plurality of tilting padsincludes at least one of polycrystalline diamond, silicon carbide,silicon nitride, cubic boron nitride, tantalum carbide, reaction-bondedsilicon carbide, reaction-bonded silicon nitride, or binderless tungstencarbide.
 3. The bearing apparatus of claim 1 wherein the maximum lateralwidth is about 12.7 cm to about 30.5 cm.
 4. The bearing apparatus ofclaim 1 wherein the maximum lateral width is about 12.7 cm to about 17.8cm.
 5. The bearing apparatus of claim 1 wherein the maximum lateralwidth is about 17.8 cm to about 25.4 cm.
 6. The bearing apparatus ofclaim 1 wherein the continuous superhard bearing element includes asuperhard table bonded to a substrate.
 7. The bearing apparatus of claim6 wherein the superhard table includes polycrystalline diamond.
 8. Thebearing apparatus of claim 1 wherein the continuous superhard bearingsurface includes at least one of silicon carbide or silicon nitride. 9.The bearing apparatus of claim 8 wherein the continuous superhardbearing surface includes at least one additional material added to thesilicon carbide or silicon nitride, the at least one additional materialincluding at least one of diamond or boron carbide.
 10. The bearingapparatus of claim 9 wherein the at least one additional material isadded to the silicon carbide or silicon nitride in an amount less thanabout 80 weight %.
 11. The bearing apparatus of claim 1 wherein thecontinuous superhard bearing surface of the continuous superhard bearingelement and the superhard bearing surface of at least one of theplurality of tilting pads comprise different materials.
 12. The bearingapparatus of claim 1 wherein the continuous superhard bearing surface ofthe continuous superhard bearing element includes silicon carbide andthe superhard bearing surface of at least one of the plurality oftilting pads includes polycrystalline diamond.
 13. The bearing apparatusof claim 1 wherein at least one of the superhard bearing surface of atleast one of the plurality of tilting pads or the continuous superhardbearing element includes a coating.
 14. The bearing apparatus of claim 1wherein at least one the continuous superhard bearing surface of thecontinuous superhard bearing element or the superhard bearing surface ofat least one of the plurality of tilting pads has a surface finish ofless than about 0.89 μm.
 15. The bearing apparatus of claim 14 whereinthe surface finish is about 0.13 μm to about 0.25 μm.
 16. The bearingapparatus of claim 13 wherein the surface finish is less than about0.064 μm.
 17. The bearing apparatus of claim 1 wherein the continuoussuperhard bearing element is brazed to the second support ring.
 18. Thebearing apparatus of claim 1 wherein the first bearing assembly is astator and the second bearing assembly is a rotor.
 19. A method ofoperating a bearing apparatus, the method comprising: rotating a rotorrelative to a stator; wherein at least one of the stator or the rotorincludes: a first support ring; and a plurality of tilting pads each ofwhich includes a superhard bearing element having a superhard bearingsurface, each of the plurality of tilting pads tilted and/or tiltablysecured relative to the first support ring; wherein the other of thestator or rotor includes: a continuous superhard bearing elementincluding a continuous superhard bearing surface that generally facessuperhard bearing element of each of the plurality of tilting pads, thecontinuous superhard bearing element having a maximum lateral widthgreater than about 12.7 cm.
 20. A method for manufacturing a bearingassembly, the method comprising forming a continuous superhard bearingelement that includes a continuous superhard bearing surface, thecontinuous superhard bearing element having a maximum lateral widthgreater than about 12.7 cm; forming a hole in the center of thecontinuous superhard bearing element; providing a support ring includinga recess configured to receive the continuous superhard bearing element;attaching the continuous superhard bearing element to the support ringsuch that the continuous superhard bearing element is secured in therecess of the support ring and the continuous superhard bearing element;and smoothing the continuous superhard bearing surface of the continuoussuperhard bearing element to exhibit a surface finish of less than 0.64μm.
 21. The method of claim 20 wherein forming a continuous superhardbearing element that includes a continuous superhard bearing surfaceincludes forming the continuous superhard bearing surface from apolycrystalline diamond table that is bonded to a substrate.